ML063490399

Relief Request 06-GO-001

ML063490399
Person / Time
Site:	Mcguire, Catawba, McGuire
Issue date:	07/27/2006
From:	Morris J Duke Energy Carolinas, Duke Power Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
06-GO-001
Download: ML063490399 (24)

Text

P Duke 6Energy July 27, 2006 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 JAMES R. MORRIS Vice President, Nuclear Support Nuclear Generation Duke Energy Corporation 526 South Church St.

Charlotte, NC 28202 Mailing Address:

EC07H / PO Box 1006 Charlotte, NC 28201-1006 704 382 6401 704 382 6056 fax james. morris@duke-energy. corn

SUBJECT:

Duke Power Company LLC d/b/a Duke Energy Carolinas, LLC (Duke)

McGuire Nuclear Station, Units 1 & 2 Docket Numbers 50-369 and 50-370 Catawba Nuclear Station, Units 1 & 2 Docket Numbers 50-413 and 50-414 Relief Request 06-GO-001 Pursuant to 10 CFR 50.55a(a)(3)(i), Duke hereby requests NRC approval to use alternatives to the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code), Section Xl inservice inspection (ISI) requirements for the McGuire and Catawba Nuclear Stations, Units 1 & 2. This proposed alternative approach is to support application of full structural weld overlays on various pressurizer nozzle-to-safe end welds and will provide an acceptable level of quality and safety.

This request is needed to support work during the following outages: McGuire Unit 1 - spring 2007, McGuire Unit 2 - fall 2006, Catawba Unit 1 - fall 2006, Catawba Unit 2 - fall 2007.

The installation of the weld overlays will be conducted in accordance with the 1998 Edition through 2000 Addenda of ASME Code,Section XI, IWA-4000 and ASME approved Code Cases N-504-2 and N-638-1 with modifications as described in this request. These Code Cases are listed as conditionally acceptable for use in NRC Regulatory Guide 1.147, Revision 14.

Additionally, Duke is required to implement Appendix VIII of the ASME Code,Section XI, 1998 Edition with the 2000 Addenda, which contains ultrasonic examination performance qualification requirements under Supplement 11 for a completed full structural weld overlay repair. In lieu of these ASME Code ultrasonic qualification requirements, Duke proposes to use the alternative qualification as administered by the Performance Demonstration Initiative (PDI) for the qualification of the ultrasonic examination of the full structural weld overlay repair, and the examination of the dissimilar metal welds.

Use of the proposed alternative is based on the PDI approved techniques and procedures also described in this request. The detailed relief request is provided I

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Nuclear Regulatory Commission July 27, 2006 Page 2 as Enclosure 1 to this letter. It contains a comprehensive set of criteria that outline the proposed McGuire and Catawba Units 1 & 2 full structural weld overlays. The relief request provides alternatives and modifications to the ASME Code requirements and Code Cases N-504-2 and N-638-1 that Duke has determined will be necessary to perform this repair.

Similar relief requests have been previously approved for Three Mile Island Nuclear Station Unit 1, on July 21, 2004; Cooper Nuclear Station on March 4, 2005; Susquehanna Steam Electric Station Unit 1, on June 22, 2005; Donald C.

Cook Nuclear Plant Unit 1 on June 27, 2005; Calvert Cliffs Nuclear Power Plant Unit 2 on July 20, 2005; and Millstone Power Station Unit 3 on January 20, 2005.

Duke requests approval of this relief request to support the McGuire Unit 2 and Catawba Unit 1 fall 2006 refueling outages. Approval is needed prior to September 16, 2006 to support the repair at McGuire.

This relief request contains one regulatory commitment. Prior to entry into Mode 4, from the McGuire Unit 2 outage in the fall of 2006, a summary of the results of the stress analyses demonstrating that the preemptive full structural weld overlay will not hinder the components from performing their design function will be submitted to the NRC. These results are expected to be bounding for all four units.

If you have any questions or require additional information, please contact Mary Shipley at (704) 382-5880.

Sincerely, James R. Morris Enclosures

Nuclear Regulatory Commission July 27, 2006 Page 3 W. D. Travers, Region II Administrator U.S. Nuclear Regulatory Commission Sam Nunn Atlanta Federal Center, 23 T85 61 Forsyth St., SW Atlanta, GA 30303-8931 J. F. Stang, Jr., Senior Project Manager (CNS & MNS)

U. S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 0-8 H 4A Rockville, MD 20852-2738 J. B. Brady NRC Senior Resident Inspector McGuire Nuclear Station E. F. Guthrie NRC Senior Resident Inspector Catawba Nuclear Station

Request No. 06-GO-001 Proposed Alternative In Accordance with 10 CFR 50.55a(a)(3)(i)

- Alternative Provides Acceptable Level of Quality and Safety -

Duke Energy Corporation McGuire and Catawba Nuclear Stations Units 1 & 2 Request for Alternative 06-GO-001 CONTENTS 1.0 ASMIE CODE COMPONENTS AFFECTED.....................................................

2 2.0 APPLICABLE CODE EDITION AND ADDENDA...................................... 3 3.0 APPLICABLE CODE REQUIREMENTS.......................................................

3 4.0 REASON FOR THE REQUEST........................................................................

4 5.0 PROPOSED ALTERNATIVES AND BASIS FOR USE...................................

4 6.0 WELD OVERLAY DESIGN AND VERIFICATION...................

7 7.0 DURATION OF THE PROPOSED ALTERNATIVES..........................................

8 8.0 PRECEDENTS.............................................

8 9.0 REFEREN CES...................................................................................................

9 10.0 C O N C LU SIO N..................................................................................

...................... 9 Figure 1.......

10 Pressurizer Nozzle Weld Overlay (Typical)............................................................

10 ATTACHMENT 1....

11 Table 1......................

12 Modifications To Code Case N-504-2 and Corresponding Non-Mandatory Appendix Q Requirem ents....................................................................................

12 T able 2............................................................................................................................

14 Alternatives to Appendix VIII, Supplement 11.....................................................

14 T able 3...................................................................................

20 Modifications to Code Case N-638-1......................................................................

20

Request No. 06-GO-001 1.0 ASME CODE COMPONENTS AFFECTED System:

Reactor Coolant System Component Number:

1PZR-W1SE LAS nozzle/Alloy 82-182 weld/SS safe end 1PZR-W2SE LAS nozzle/Alloy 82-182 weld/SS safe end rressunzer xenei nozzie to sate ena Ou 1r2*K-wiE LAS nozzietiuloy 82-82. weia/6 safe ena Pressurizer Safety nozzle to safe end 8" OD IPZR-W4ASE LAS nozzle/Alloy 82-182 weld/SS safe end Pressurizer Safety nozzle to safe end 8" OD 1PZR-W4BSE LAS nozzle/Alloy 82-182 weld/SS safe end Pressurizer Safety nozzle to safe end 8" OD 1PZR-W4CSE LAS nozzle/Alloy 82-182 weld/SS safe end RC Pipe Surge safe end to pipe 14" Sch 160 NC1F3612 SS safe end/SS weld/SS pipe RC Pipe Spray safe end to Pipe 4" Sch 160. NC1F1746 SS safe end/SS weld/SS pipe RC Pipe Relief safe end to Pipe 6" Sch 160 NC1F546 SS safe end/SS weld/SS pipe RC Pipe Safety safe end to Pipe 6" Sch 160 NC1F542 SS safe end/SS weld/SS pipe RC Pipe Safety safe end to Pipe 6" Sch.160 NC1F544 SS safe end/SS weld/SS pipe RC Pipe Safety safe end to Pipe 6" Sch 160 NC1F1850 SS safe end/SS weld/SS pipe Pressurizer Surge nozzle to safe end 15" OD 2PZR-W1SE ILAS nozzle/Alloy 82-182 weld/SS safe end

'Pressurizer Spray nozzle to safe end 6" OD 2PZR-W2SE LAS nozzle/Alloy 82-182 weld/SS safe end Pressurizer Relief nozzle to safe end 8" OD 2PZR-W3SE LAS nozzle/Alloy 82-182 weld/SS safe end Pressurizer Safety nozzle to safe end 8" OD 2PZR-W4ASE ILAS.nozzl e/Alloy 82-182 weld/SS safe endI RPr riper Spaetyo safe end t

e h

12PZR-W4BSE LAS nozzle/Alloy 82-182 weld/SS safe end IPressurizerj Safety nozzl tosf 3n

" OD 12PZR-W4CSE ILAS nozzle/Alloy 82-182 weld/SS safe end RC Pipe Surge safe end topipe 14" Sch 160 iNC2FW2-3 SS safe end/SS weld/SS pipe RC Pipe ISSpray safe end to Pipe 4" Sch 160 jNC2FW13-1 SS safe end/SS weld/SS pipe RC Pipe

]Relief safe end to Pipe 6" Sch 160 NC2FW61-1 jSS safe end/SS weld/SS pipe RC Pipe

]Safety safe end to Pipe 6" Sch 160 INC2FW53-12 SS safe end/SS weld/SS pipe RCPipes i Safety safe end to Pipe 6"Sch 160 iNC2FW53-13 LSS safenend/SSAweld/SS pipe RC Piper r

Safety safe end to Pipe 6" Sch 160 PNC2FW53A26 SS safe end/SS weld/SS pipe PressurizeruRgele nozzle to safe end 85" OD

]1PZR-WlSE JLAS nozzle/Alloy 82-182 weld/SS safe end Pressurizer Spafey nozzle to safe end 8" OD 1PZR-W42SE LAS nozzle/Alloy 82-182 weld/SS safe end IPressurizer Saetye nozzle to safe end 8" OD 1PZR-W43SE LAS nozzle/_Alloy 82-182 weld!SS safe end PressurizerJSafety nozzle to safe end1 8" OD 1PZR-W4CSE LAS nozzle/Alloy 82-182 weld/SS safe end RC Pipe jSurge safe end to pipe 114"_Sch 160 1NC26-3 SS safe end/SS weld/SS pipe RC Pipe JSpray safe end to Pipe* J4"_Sch 160 1.NC190-24 JSS safe end/SS weld/SS pipe RC Pipe ~Relief safe end to Pipe j 6"_Sch 160 1NC173-1

~SS safe end/SS weld/SS pipe

• RC Pipe lSafety safe end to Pipe 6" Sch 160 1NC227-1 ~SS safe end/SS weld/SS pipe

.RC Pipe

] Safety safe end to Pipe 16"_Scl 160 1NC258-1 JSS safe end/SS weldISS pipe iRPipe ISafecv Safe end to Pipe i6"Sc f160 C22,4-1,

S saetdS wl/Spp

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i,.M'-,gmosfeedS el/Spp

Request No. 06-GO-001 Enclosure I.

Pressurizer Surge nozzle to safe end 15" OD 2PZR-W1SE LAS nozzle/Alloy 82-182 weld/SS safe end Pressurizer Spray nozzle to safe end 6" OD 2PZR-W2SE LAS nozzle/Alloy 82-182 weld/SS safe end Pressurizer Relief nozzle to safe end 8" OD 2PZR-W4CSE LAS nozzle/Alloy 82-182 weld/SS safe end Pressurizer Safety nozzle to safe end 8" OD 2PZR-W4ASE LAS nozzle/Alloy 82-182 weld/SS safe end Pressurizer Safety nozzle to safe end 8" OD 2PZR-W4BSE LAS nozzle/Alloy 82-182 weld/SS safe end Pressurizer Safety nozzle to safe end 8" OD 2PZR-W3SE LAS nozzle/Alloy 82-182 weld/SS safe end RC Pipe Surge safe end to pipe 14" Sch 160 2NC8-3 SS safe end/SS weld/SS pipe RC Pipe Spray safe end to Pipe 4" Sch 160 2NC44-28 SS safe end/SS weld/SS pipe RC Pipe Relief safe end to Pipe 6" Sch 160 2NC117-7 SS safe end/SS weld/SS pipe RC Pipe Safety safe end to Pipe 6" Sch 160 2NC119-1 SS safe end/SS weld/SS pipe RC Pipe Safety safe end to Pipe 6" Sch 160 2NC163-1 SS safe end/SS weld/SS pipe RC Pipe Safety safe end to Pipe 6" Sch 160 2NC112-5 SS safe end/SS weld/SS pipe (1)

LAS = SA-508Class 2 Grade 2 low alloy steel.

SS = Type 316 austenitic stainless steel Code Class:

Class 1 Examination Category:

Code Item Number:

McGuire - R-A (Risk-Informed)

Catawba - B-F; B-J McGuire - R01.011 Catawba - B5.40; B9.11 2.0 APPLICABLE CODE EDITION AND ADDENDA Inservice Inspection:

ASME Boiler and Pressure Vessel Code,Section XI, 1998 Edition through 2000 Addenda - McGuire Units 1 & 2, Catawba Units 1 & 2 Design and Fabrication:

ASME Boiler and Pressure Vessel Code,Section II, 1971 Edition through Winter 1971 Addenda - McGuire Units I & 2 ASME Boiler and Pressure Vessel Code, Section lIi, 1974 Edition through Summer 1974 Addenda - Catawba Units 1 & 2 Duke Welding Program:

ASME. Boiler and Pressure Vessel Code, Section 111, 1989 Edition No Addenda - All units at all sites 3.0 APPLICABLE CODE REQUIREMENTS ASME Boiler and Pressure Vessel Code, Section XM, 1998 Edition through 2000 Addenda, Article IWA-4000, "Repair/Replacement Activities"

Request No. 06-GO-00 1 ASME Boiler and Pressure Vessel Code,Section X), 1998 Edition through 2000 Addenda, Appendix VIII, Supplement 11, "Qualification Requirements for Full Structural Overlaid Wrought Austenitic Piping Welds" Code Case N-504-2 with requirements of ASME Code,Section X), Nonmandatory Appendix Q, "Weld Overlay Repair of Class 1, 2, and 3 Austenitic Stainless Steel Piping Weldments" Code Case N-638-1, "Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique".

4.0 REASON FOR THE REQUEST Dissimilar metal welds (DMW) made with nickel alloys 82 and 182 have been shown to be susceptible to primary water stress corrosion cracking (PWSCC) degradation in components such as the pressurizer that are subjected to higher operating temperatures. Structural weld overlays have been used for several years on piping of both boiling water reactors and pressurized water reactors to arrest the growth of existing flaws while establishing a new structural pressure boundary. No evidence of PWSCC has been found in the welds of the McGuire or Catawba pressurizer; however, PWSCC is difficult to detect in DMW except when the inspection is performed in accordance with the stringent requirements of ASME Section XI, Appendix VIII. The DMW included in this request for relief have been evaluated and found not to meet the surface or geometric requirements of Appendix VIII. The feasibility of modifying the geometry to an acceptable configuration has not been established.

Duke is proposing to take a proactive approach to apply a preemptive full structural weld overlay (PWOL) to the dissimilar metal welds of the pressurizer components listed in Section 1.0 of this request.

Currently, there are no comprehensive criteria for a licensee to apply a full structural weld overlay to DMW constructed of Alloy 82/182 weld material. Neither the latest NRC approved edition nor the edition of ASME Section XI used for the McGuire and Catawba Units I & 2 repair/replacement program, contains the needed requirements for this type of repair. Repair/replacement activities associated with a full structural weld overlay repair of this type are required to address the materials, welding parameters, ALARA concerns, operational constraints, examination techniques, and procedure requirements. Similar nozzle-to-safe end weld overlays have been applied to other plants since 1986 with no problems identified.

5.0 PROPOSED ALTERNATIVES AND BASIS FOR USE Pursuant to !0CFR 50.55a(a)(3)(i), an alternative to the requirements listed in Section 3.0 above is requested on the basis that the proposed alternative will provide an acceptable level of quality and safety. Attachment 1, Tables 1, 2, and 3, included as a part of this request for relief, provides details of relief requested from each of these requirements.'

A full structural PWOL is proposed for each of the pressurizer welds identified in Section 1.0 above. The overlays will extend around the full circumference of the nozzle-to-safe end and

Request No. 06-GO-001 safe end to piping welds, as illustrated in Figure 1. The stainless steel weld connecting the pipe to the safe end is included due to the close proximity to the dissimilar metal weld and the need to provide a length of overlay adequate to assure that adequate volumetric coverage for non-destructive examination will be obtained. The full structural weld overlays are sized to satisfy the ASME Code, Section IIJ requirements without crediting the existing welds.

The proposed weld overlay design is consistent with the requirements of ASMIE Code Case N-504-2 and Section XI, Nonmandatory Appendix Q with the modifications noted in Table 1.

The provisions of Appendix Q must be met as a condition of acceptance of the Code Case by NRC Regulatory Guide 1.147, Revision 14. The specific thickness and length are computed according to the guidance provided in Code Case N-504-2 and Appendix Q. The overlay will completely cover the Alloy 82/182 and adjacent stainless steel welds with alloy 52M152MS material that is highly resistant to PWSCC.

The length of the full structural weld overlay is sized for inspection of the volume shown in Appendix Q, Fig Q-4300-1. This volume extends 1/22-inch beyond the susceptible weld and includes the outer 25% of the original wall thickness. The length of the PWOL is extended and blended into the low alloy steel nozzle outer diameter taper to permit ultrasonic testing (UT) of the weld and to minimize stress concentration on the nozzle outer diameter. The outside diameter of the nozzle is larger than that of the adjacent component; therefore, the PWOL thickness on the component is increased to allow a smooth transition surface for UT.

The final structural weld overlay length and thickness after taking into consideration the UT requirements will exceed the length required for a full structural weld overlay repair in accordance with Code Case N-504-2 and Appendix Q.

Appendix Q, Section 4000 requires ultrasonic procedures and personnel to be qualified in accordance with ASME Code,Section XI, Appendix VIII. Ultrasonic examination of the completed PWOL will be accomplished in accordance with Section XI, Appendix VIII, Supplement 11, with alternatives to comply with the Performance Demonstration Initiative (PDI) program as shown in Table 2.

Implementation of Section XI, Subsection, IWA-4540(a)(2) for a system leakage test requires performance of NDE in accordance with the methods and acceptance criteria of the applicable Subsection of the 1992 or later Edition of ASME Section III. Alternately, the NDE requirements of Appendix Q will be followed for the required NDE. The bases for these alternatives are shown as needed in Table 1.

The PWOL will be applied over portions of the low alloy steel (LAS) nozzles. The Construction Code requires post-weld heat treatment after welding. As an alternative to post-weld heat treatment, the overlay will be implemented in accordance with Code Case N-638-1 with the modifications noted in Table 3 of Attachment 1. Code Case N-638-1 was conditionally approved for generic use in NRC Regulatory Guide 1.147, Revision 14, and was developed for welding similar and dissimilar metals using the ambient temperature machine GTAW temper bead technique. This Code Case specifies a limit of 100 square inches for the surface area of temper bead weld over the ferritic material. The weld surface areas over ferritic material for the subject weld overlays are expected to be approximately 120 square

Request No. 06-GO-001 inches, 55 square inches, and 33 square inches, for the surge line nozzles, safety and relief line nozzles, and spray line nozzles, respectively.

Recently ASME approved Code Case N-638-3 increases the limit for temper bead welding over ferritic material. The technical basis for this revision is contained in a white paper that was submitted to the Code Committee as part of the ASME Code approval process. The white paper indicates the original limit of 100 square inches in Code Case N-638-1 was an arbitrary limit and goes on to justify the application of overlays up to 500 square inches on ferritic low alloy steel. The white paper was also submitted to the NRC as a part of a relief request by Constellation Energy Generation Group (Adams Accession Number, ML060240110). The white paper cites evaluations of a 12 inch diameter nozzle weld overlay to demonstrate adequate tempering of the weld heat affected zone (Section 2a of the white paper), residual stress evaluations demonstrating acceptable residual stresses in weld overlays ranging from 100 to 500 square inches (Section 2b of the white paper), and service history in which weld repairs exceeding 100 square inches were NRC approved and applied to DMW nozzles in several BWRs and three PWRs (Section 3c of the white paper). Some of the cited repairs are greater than 15 years old, and have been inspected several times with no evidence of any continued degradation. The revised limit far exceeds the estimated 120 square inches to be applied to the McGuire and Catawba surge nozzles and so provides a conservative basis for application of the proposed PWOL.

Temperature monitoring required by Code Case N-638-1 will be performed using temporarily attached pyrometers and manual data recording in lieu of thermocouples and recording equipment required by IWA-4610(a) of Section XI. The adequacy of contact pyrometers for this purpose has been recognized by ASME and this option is included in Code Case N-638-3.

This exception has been permitted by the NRC in the past (see precedent 6 in Section 8.0 below). As described in Table 3, use of pyrometers will provide acceptable temperature monitoring for application of the PWOL.

In lieu of the inspections required by Code Case N-638-1 and the condition for approval in Reg. Guide 1.147, inspections will be performed in accordance with Code Case N-504-2 and Section XI, Appendix Q. Code Case N-638-1 applies to any type of welding where a temper bead technique is to be employed and is not specifically written for a weld overlay repair.

The specific overlay inspections required by Code Case N-504-2 will detect any discontinuities that might result from application of the PWOL and will provide assurance equal to that provided by the inspections required in Code Case N-638-1.

In summary, this letter requests relief from portions of the applicable ASME Code and Code Cases approved for use by the NRC. There are no new or different approaches in this overlay design that are considered first of a kind or inconsistent with previous applications. The overlay is designed as a full structural overlay in accordance with ASME Code Case N-504-2 and Section XL, Nonmandatory Appendix Q

Request No. 06-GO-001 6.0 WELD OVERLAY DESIGN AND VERIFICATION The design of these weld overlays takes guidance from the requirements of ASME Code Case N-504-2, and Code Case N-638-1, with modifications as described above in Section 5.0 and in the attached tables. The weld overlays will be demonstrated to be long-term repairs and mitigation of PWSCC based on analyses that will be completed before plant restart. The fundamental design basis for full structural weld overlays is to maintain the original safety margins of the welds, with no credit taken for the underlying PWSCC susceptible weldments.

Analyses are performed to demonstrate that the overlay designs meet the requirements of ASME Code, Section XU, IWB-3640, in addition to the structural requirements of ASME Code Case N-504-2 for full structural weld overlays. No credit is taken for the diluted first layer of the overlays over the PWSCC susceptible weldments. Each required analysis will be bounding for the four units included in this request for relief. Following is a listing of the analyses and verifications that will be performed:

1. Nozzle specific stress analyses will be performed to establish a residual stress profile in the nozzle. Severe ID weld repairs have been assumed that effectively bound any actual weld repairs to the nozzle. The weld overlay is subsequently applied to simulate the final residual stress profile. Post weld overlay residual stresses at normal operating conditions will then be shown to result in beneficial compressive stresses on the inside surface of the components, further assuring that crack growth into the overlay is highly unlikely.

2. Fracture mechanics analyses will also be performed to predict crack growth, assuming that cracks exist that are equal to or greater than the thresholds of the NDE techniques to be used on the nozzles. Potential crack growth will be evaluated due to PWSCC as well as due to fatigue crack growth in the original DMW. The crack growth analyses will consider all design loads and transients, plus the post weld overlay residual stress distributions, and will demonstrate that cracks will not grow beyond the original DMW thickness for the time period until the next scheduled inservice inspection.

_ 3. The analyses will demonstrate that application of the weld overlays does not impact the conclusions of the existing nozzle Stress Reports. ASME Code,Section III stress and fatigue criteria will be met, as spelled out in ASME Code Case N-504-2.

4. Shrinkage will be measured during the overlay application. Shrinkage stresses at other locations in the piping systems arising from the weld overlays will be demonstrated not to have an adverse effect on the systems. Clearances of affected support and restraints will be checked after the overlay repair, and will be reset within the design ranges as required.

5. The total added weight on the piping systems due to the overlays will be evaluated for potential impact on piping system stresses and dynamic characteristics.

Request No. 06-GO-001

6. The as-built dimensions of the weld overlays will be measured and evaluated to demonstrate that they equal or exceed the minimum design dimensions of the overlays.

Summaries of the results of the analyses listed in items 1 through 3 above will be submitted to the NRC prior to entry into Mode 4. Items 4 through 6 will be done after completion of the PWOLs and will be available for review.

7.0 DURATION OF THE PROPOSED ALTERNATIVES These structural weld overlays will remain in place for the design life of the repair that is defined by the evaluation required in paragraph (g) of Code Case N-504-2 and corresponding requirements in Nonmandatory Appendix Q.

8.0 PRECEDENTS

1.

Letter from Richard J. Laufer, NRC, to Christopher M. Crane, AmerGen, "Three Mile Island Nuclear Station, Unit 1 (TMI-1) Request for Relief from Flaw Removal, Heat Treatment, and Nondestructive Examination Requirements for the Third 10-year Inservice Inspection (ISI) Interval (TAC.No. MC1201)," Accession Number ML041670510, dated July 21, 2004.

2.

Letter from Richard J. Laufer, NRC, to Bryce L. Shriver, PPL Susquehanna, "Susquehanna Steam Electric Station, Unit 1 - Relief from American Society of Mechanical Engineers, Boiler and Pressure Vessel Code (ASME Code),Section XI, Appendix VIII, Supplement 11, Requirements and Code Cases N-504-2 and N-638 Requirements (TAC Nos. MC2450, MC2451 and MC2594)," Accession Number IvlL051220568, dated June 22, 2005.

3.

Letter from L. Raghavan, NRC, to Mano K. Nazar, I&M, "Donald C. Cook Nuclear Plant, Unit 1 - Alternative to Repair Requirements of Section XI of the American Society of Mechanical Engineers Code (TAC No. MC06751)," Accession Number ML051720006, dated June 27, 2005.

4.

Letter from Richard J. Laufer, NRC, to George Vanderheyden, Calvert Cliffs, "Calvert Cliffs Nuclear Power Plant, Unit No. 2 - Relief Request for Use Weld Overlay and Associated Alternative Inspection Techniques (TAC Nos. MC6219 and MC6220),"

Accession Number ML051930316, dated July 20, 2005.

5.

Letter from Darrell J. Roberts, NRC, to David A. Christian Dominion Nuclear Connecticut, Inc., "M1illstone Power Station, Unit No. 3 - Issuance of Relief from Code Requirements (TAC No. MC8609)," Accession Number ML053260012, dated January 20, 2006.

6.

Southern (California Edison's San Onofre Unit 2, verbal authorization given on March 23, 2006:;,and

Request No. 06-GO-001

7.

First Energy's Davis Besse Unit 1, verbal authorization given on April 5, 2006.

9.0 REFERENCES

(1)

ASME Code, Section XM, 1998 Edition through 2000 Addenda, Article JWA-4000.

(2)

ASME Code,Section XI, 1998 Edition through 2000 Addenda, Mandatory Appendix VIII, Supplement 11.

(3)

ASME Code Case N-504-2, Alternative Rules for Repair of Class 1, 2, and 3 Austenitic Stainless Steel Piping,Section XI, Division 1, March 12, 1997.

(4)

ASME Code Section XI, through 2005 Addenda, Nonmandatory Appendix Q, Weld Overlay Repair of Class 1, 2, and 3 Austenitic Stainless Steel Piping Weldments.

(5)

ASME Code Case N-638-1, Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique,Section XI, Division 1, February 13, 2003.

(6)

ASME Code Case N-638-3, Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique,Section XI, Division 1, April 18, 2006 & accompanying white paper.

(7)

Calvert Cliffs, Units 1 & 2 - ASME Section XI Relief Request to Use Weld Overlay & Associated Alternative Techniques, Accession Number ML060240110, dated January 18, 2006.

10.0 CONCLUSION

Duke concludes that the alternative repair approach described above presents an acceptable level of quality and safety to satisfy the requirements of 10 CFR 50.55a(a)(3)(i). The approach described in this relief request includes evaluation of available operating experience related to previously NRC approved applications of overlays to DMW.

Request No. 06-GO-001 GrJA 01 2V or 2a:

-SAF1' QZZ LC ALLOY $2/-1a27 UED/TJTER F31 6L END Figure 1 Pressurizer Nozzle Weld Overlay (Typical)

Request No. 06-GO-001 ATTACHMENT 1 CONTENTS Table 1 Modifications to Code Case N-504-2 and Corresponding Non-Mandatory Appendix Q Requirements Table 2 Alternatives to Appendix VIII, Supplement 11 Table 3 Modifications to Code Case N-638-1

Request No. 06-GO-001 Table 1 Modifications To Code Case N-504-2 and Corresponding Non-Mandatory Appendix Q Requirements Code Case N-504-2 Modification/Basis Modification. Code Case N-504-2 will be used for weld overlay repairs to the ferritic (P3) and nickel alloy (F43/P43) base material as well as the Reply: It is the opinion of the Committee that, in lieu of the requirements of austenitic stainless steel (P8) base material.

IWA-4120 in Editions and Addenda up to and including the 1989 Edition Basis: Code Case N-504-2 is accepted for use along with Nonmandatory Nvith the 1990 Addenda, in IWA-4170(b) in the 1989 Edition with the 1991 Appendix Q in the current NRC Regulatory Guide 1.147 Rev. 14. For the Addenda up to and including the 1995 Edition, and in IWA-4410 in the 1995 weld overlay of the identified welds at McGuire and Catawba Units I & 2 Edition with the 1995 Addenda and later Editions and Addenda, defect in the base material will beferritic material (P3) with existing nickel alloy weld austenitic stainless steel piping may be reduced to a flaw of acceptable size metal (F43/P43) to which an austenitic stainless steel (P8) safe end is in accordance with IWB-3640 from the 1983 Edition with the Winter 1985 welded. Industry operational experience has shown that PWSCC in Alloy Addenda, or later Editions and Addenda, by deposition of weld 82/182 will blunt at the interface with stainless steel base metal, ferritic base reinforcement (weld overlay) on the outside surface of the pipe, provided the* metal, or Alloy 52/52M/52MS weld metal. The 360'structural weld overlay following requirements are met. [Essentially same as Scope of will control growth in any PWSCC crack and maintain weld integrity. The Appendix Q]:

weld overlay will induce compressive stress in the weld, thus impeding growth of any reasonably shallow cracks. Furthermore, the overlay will be sized to meet all structural requirements independent of the existing weld.

Modification. In lieu of austenitic stainless steel filler material, the, reinforcement weld metal will be a nickel alloy.

Basis: The weld metal used may be ERNiCrFe-7A (Alloy 52M, UNS N06054) or ERNiCrFe-7 (Alloy 52 UNS N06052). This weld metal is assigned F43 by ASME per Code Case 2142-2. The requirements of ASME Section Ill, NB-2400 will be applied to allfiller material. The chromium content ofAlloy 52M/MS is28-31.S%, identical to that of Alloy 52. The main difference in (b) Reinforcement weld metal shall be low carbon (0.035% max.) austenitic A

stainless steel applied 3600 around the circumference of the pipe, and shall be Alloy 52 vs. Alloy 52M/MS is a higher Niobium content (0.5-1 %). The deposited in accordance with a qualified welding procedure specification difference in chemical composition between Alloy 52 and Alloy 52MIMS identified in the Repair Program. [Same as Q-2000(a)]

improves the weld-ability of the material and pins the grain boundaries thus preventing separation between the grains and hot tearing during weld puddle solidification. These filler materials were selected for their improved resistance to PWSCC. Alloys 52 and 52M/MS contain about 30% chromium that imparts excellent corrosion resistance. The existing Alloy 82/182 weld and the Alloy 52M/52MS overlay are nickel base and have ductile properties and toughness similar to austenitic stainless steel piping welds at pressurized water reactor operating temperature. These filler materials are suitable for welding over the ferritic nozzle, Alloy 82/182 weld, and the austenitic Page 12 of 21

Request No. 06-GO-001 Table 1 Modifications To Code Case N-504-2 and Corresponding Non-Mandatory Appendix Q Requirements Code Case N-504-2 Modification/Basis stainless steel safe end or pipe components.

(e) The weld reinforcement shall consist of a minimum of two weld layers having as-deposited delta ferrite content of at least 7.5 FN. The first. layer of Modification: Delta ferrite (FN) measurements will not be performed for weld metal with delta ferrite content of least 7.5 FN shall constitute the first weld overlay repairs made of Alloy 52/52M152MS weld metal.

layer of the weld reinforcement design thickness. Alternatively, first layers Basis: Welds of Alloy52/52M/52MS are 100% austenitic and contain no of at least 5 FN may be acceptable based on evaluation. [Sanie as Q-deltaferrite due to the high nickel composition (approximately 60% nickel).

2000(d)]

Modification: If a flaw or evidence of a flaw is observed, in lieu of hydrostatic testing, a system leakage test and an ultrasonic examination (UT)

Pressure Testing of the weld overlay will be performed consistent with ASME IWA-(hs) The completed repair shall be pressure tested in accordance with IWA-4540(a)(2), as modified by Nonmandatory Appendix Q.

5000. If the flaw penetrated the original pressure boundary prior to welding, Basis: Application of IWA-4540(a)(2) for a system leakage test in lieu of a or if any evidence of a flaw penetrating the pressure boundary is observed system hydrostatic test requires performance of NDE in accordance with the or i an evdene o a law eneratng he resure ounaryis bseved methods and acceptance criteria of the applicable Subsection of the 1992 during the welding operation, a system hydrostatic test shall be performed in Etion acctin IIa of the III Subsection NB tie 5000 accordance with IWA-5000. If the system pressure boundary has not been d

ition oon aSMe Sect ubseci NBertice penetrated, a system leakage, inservice, or functional test shall be performed configuration. The NDE addrements of Nonmascatory Appendix Q will be in accordance with IWA-5000.

cofgrto.TeNEreqie ntofNmadaryApdxQwllb followed for the required NDE in lieu of ASME Section III. Code Case N-504-2 and Nonmandatory Appendix Q provide appropriate examination requirements including examination volume, acceptance criteria, and examinationl methods per Appendix VII1.

0 Page 13 of 21

Request No. 06-GO-001 Table 2 Alternatives to Appendix VIII, Supplement 11 Appendix VIII of Section Xl cannot be used for NDE of a structural weld overlay repair. Relief is requested to use the PDI program implementation of Appendix VIII. A detailed comparison of Appendix VIII and PDI requirements is summarized below.

Relief is requested to allow closer spacing of flaws provided the flaws do not interfere with detection or discrimination of other discontinuities. The specimens used for qualification to the Tri-party (NRC/BWROG/EPRI) agreement have a flaw population density greater than allowed by current Code requirements. These samples have been used successfully for all previous qualifications under the Tri-party agreement program. To facilitate their use and provide continuity from the

-Tri-party agreement program to Supplement 11, the PDI program has merged the Tri-party test specimens into their structural weld overlay program.

SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR PD! PROGRAM:

FULL STRUCTURAL OVERLAID WROUGHT AUSTENITIC The Proposed Alternative to Supplement 11 Requirements PIPING WELDS 10 SPECIMEN REQUIREMENTS 1.1 General. The specimen set shall'conform to the following requirements.

(b) The specimen set shall consist of at least three specimens having different nominal pipe diameters and overlay thicknesses. They shall include the minimumandmaximumnominal pipe diameters and overlayt.

hey shal i ex ath n Alternative: (b) The specimen set shall include specimens with overlays not thicker than 0.1 inch more than the minimum thickness, nor thinner than 0.25 procedure is applicable. Pipe diameters within a range of 0.9 to 1.5 limes a nominal diameter shall be considered equivalent. If the procedure is applicable inchdfte maxim n l on to pipe diameters of 24 inch or larger, the specimen set must include at least procedure is applicable.

one pecmen24 ich r lrgerbutnee no incudethemaxium iamter Basis: To avoid confusion, the overlay thickness tolerance contained in the one specim en 24 inch or larger but need not include the m axim um diam eter.

la ts n e c w s r wo d d n.th p r se " d t e n ai e h ll b The specimen set must include at least one specimen with overlay thickness ltentence was rw ded tn the phrasenthe inderash be within -0.1 inch to +0.25 inch of the maximum nominal overlay thickness for alternative flaws" was added to the next to last sentence in paragraph 1.1 (d) which the procedure is applicable.

(1).

(d) Flaw Conditions (I) Base metal flaws. All flaws must be cracks in or near the - butt weld heat-Alternative: (1)... must be in or... intentional overlay fabrication flaws shall affected zone, open to the inside surface, and extending at least 75% through not interfere with ultrasonic detection or characterization of the base metal the base metal wall. Flaws may extend 100% through the base metal and into flaws. Specimens containing intergranular stress corrosion cracking shall be the overlay material; in this case, intentional overlay fabrication flaws shall usedwhen available. At least 70% of the flaws in the detection and sizing tests not interfere with ultrasonic detection or characterization of the cracking.

shall be cracks and the remainder shall be alternative flaws. Alternative flaw Page 14 of 21

Request No. 06-GO-001 Table 2 Alternatives to Appendix VIII, Supplement 11 SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR FULL STRUCTURAL OVERLAID WROUGHT AUSTENITIC PIPING WELDS PDI PROGRAM:

The Proposed Alternative to Supplement 11 Requirements Specimens containing IGSCC shall be used when available.

mechanisms, if used, shall provide crack-like reflective characteristics and shall be limited by the following:

(a) The use of alternative flaws shall be limited to when the implantation of cracks produces spurious reflectors that are uncharacteristic of actual flaws.

(b) Flaws shall be semi elliptical with a tip width of less than or equal to 0.002 inches.

Basis: This paragraph requires that all base metal flaws be cracks.

Implanting a crack requires excavation of the base material on at least one side of the flaw. While this may be satisfactory for ferritic materials, it does not produce a useable axial flaw in austenitic materials because the sound beam, which normally passes only through base material, must now travel through weld material on at least one side, producing an unrealistic flaw response. To resolve this issue, the PDlprogram revised this paragraph to allow use of alternative flaw mechanisms under controlled conditions. For example, alternative flaws shall be limited to when implantation of cracks precludes obtaining ah effective ultrasonic response, flaws shall be semi elliptical with a tip width of less than or equal to 0.002 inches, and at least 70% of the flaws in the detection and sizing test shall be cracks and the remainder shall be alternative flaws. To avoid confusion, the overlay thickness tolerance contained in paragraph 1.1(b) last sentence, was reworded and the phrase "and the remainder shall be alternative flaws" was added to the next to last sentence. Paragraph 1.1(d)(1) includes the statement that intentional overlay fabrication flaws shall not interfere with ultrasonic detection or characterization of the base metal flaws.

(e) Detection Specimens i

(1) At least 20% but less than 40% of the flaws shall be oriented within +/-200 of the pipe axial direction. The remainder shall be oriented circumferentially.

Flaws shall not be open to any surface to which the candidate has physical or visual access, The rules of IWA-3300 shall be used to determine whether closely spaced flaws should be treated as single or multiple flaws.

Alternative: (1) At least 20% but less than 40% of the base metal flaws shall be oriented within +/-200 of the pipe axial direction. The remainder shall be oriented circumferentially. Flaws shall not be open to any surface to which the candidate has physical or visual access.

Basis: The requirement for axially oriented overlay fabricationflaws was excluded from the PDI Program as an improbable scenario. Weld overlays are typically applied using automated GTA W techniques with the filler metal applied in a circumferential direction. Because resultant fabrication induced discontinuities would also be expected to have major dimensions oriented in the circumferential direction axial overlay fabrication flaws are unrealistic.

Page 15 of 21

Request No. 06-GO-001 Enclosure I Table 2 Alternatives to Appendix VIII, Supplement 11 SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR PDI PROGRAM:

FULL STRUCTURAL OVERLAID WROUGHT AUSTENITIC The PtOSupMe PIPING WELDS The Proposed Alternative to Supplement 11 Requirements The requirement for using IWA-3300 for proximity flaw evaluation was excluded; instead indications will be sized based on their individual merits.

Alternative: (2) Specimens shall be divided into base metal and overlay fabrication grading units. Each specimen shall contain one or both types of (2) Specimens shall be divided into base and overlay grading units. Each grading units. Flaws shall not interfere with ultrasonic detection or specimen shall contain one or both types of grading units.

characterization of other flaws.

Basis: Inclusion of "metal" and 'fabrication" provides clarification. Flaw identification is improved by ensuring flaws are not masked by other flaws.

Alternative: (a)(1) A base metal grading unit includes the overlay material and the outer 25% of the original overlaid weld. The base metal grading unit shall extend circumferentially for at least 1 inch and shall start at the weld centerline and be wide enough in the axial direction to encompass one half of (a)(1) A base grading unit shall include at least 3 inch of the length of the the original weld crown and a minimum of 0.50" of the adjacent base material.

overlaid weld. The base grading unit includes the outer 25% of the overlaid Basis: The phrase "and base metal on both sides," was inadvertently included weld and base metal on both sides. The base grading unit shall not include the in the description of a base metal grading unit, The PD! program intentionally inner 75% of the overlaid weld and base metal overlay material, or base metal excludes this requirement because some of the qualification samples include to-overlay Interface, flaws on both sides of the weld. To avoid confusion several instances of the term "cracks" or "cracking" were changed to the terin "flaws" because of the use of alternative Flaw mechanisms. Modified to require that a base metal grading unit include at leastl inch of the length of the overlaid weld, rather than 3 inches.

Alternative: (a)(2) When base metal flaws penetrate into the overlay material, (a)(2) When base metal cracking penetrates into the overlay material, the base the base metal grading unit shall not be used as part of any overlay fabrication grading unit shall include the overlay metal within 1 inch of the crack grading unit.

location. This portion of the overlay material shall not be used as part of any Basis: Substituted terms provide clarification and are consistent with ld(1) overlay grading unit.

above. The PD! program adjusts for this conservative change for excluding this type grading unit.

(a)(3) When a base grading unit is designed to be unflawed, at least 1 inch of Alternative: (a)(3) Sufficient unflawed overlaid weld and base metal shall unflawed overlaid weld and base metal shall exist on either side of the base exist on all sides of the grading unit to preclude interfering reflections from grading unit. The segment of weld length used in one base grading unit shall adjacent flaws.

not be used in another base grading unit. Base grading units need not be Basis: Modified to require sufficient unflawed overlaid weld and base metal to Page 16 of 21

Request No. 06-GO-001 Table 2 Alternatives to Appendix VIII, Supplement 11 SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR PDI PROGRAM:

FULL STRUCTURAL OVERLAID WROUGHT AUSTENITIC PIPING WELDS The Proposed Alternative to Supplement 11 Requirements uniformly spaced around the specimen.

exist on all sides of the grading unit to preclude interfering reflections from adjacent flaws, rather than the I inch requirement.

Alternative: (b)(1) An overlay fabrication grading unit shall include the overlay material and the base metal-to-overlay interface for a length of at least 1 inch (b)(1) An overlay grading unit shall include the overlay material and the base Basis: The PDlprogram reduces the base metal-to-overlay interface to at metal-to-overlay interface of at least 6 in2. The overlay grading unit shall be least I inch (in lieu of a minimum of 2 inches) and eliminates the minimum rectangular, with minimum dimensions of 2 Inch rectangular dimension. This criterion is necessary to allow use of existing examination specimens that were fabricated in order to meet NRC Generic Letter 88-01. This criterion may be more challenging than the ASME Code because of the variability associated with the shape of the grading unit.

Alternative: (b)(2) Overlay fabrication grading units designed to be unflawed shall be separated by unflawed overlay material and unflawed base metal-to-overlay interface for at least 1 inch at both ends. Sufficient unflawed overlaid (b)(2) An overlay grading unit designed to be unflawed shall be surrounded by weld and base metal shall exist on both sides of the overlay fabrication unflawed overlay material and unflawed base metal-to-overlay interface for at grading unit to preclude interfering reflections from adjacent flaws. The least 1 inch around its entire perimeter. The specific area used in one overlay specific area used in one overlay fabrication grading unit shall not be used in another overlay fabrication grading unit. Overlay fabrication grading units grading unit shall not be used in another overlay grading unit. Overlay grading need not be spaced uniformly about the specimen.

units need not be spaced uniformly about the specimen.

ne o esae nfrl bu h pcmn nt Basis: Paragraph 1. 1 (e)(2)(b)(2) states that overlay fabrication grading units designed to be unflawed shall be separated by unflawed overlay material and unflawed base metal-to-overlay interface for at least I inch at both ends, rather than around its entire perimeter.

Alternative:...base metal grading units, ten unflawed base metal grading (b)(3) Detection sets shall be selected from Table VIII-S2-1. The minimum units, five flawed overlay fabrication grading units, and ten unflawed overlay detection sample set is five flawed base grading units, ten unflawed base fabrication grading units. For each type of grading unit, the set shall contain at grading units, five flawed overlay grading units, and ten unflawed overlay least twice as many unflawed as flawed grading units. For initial procedure grading units. For each type of grading unitthe set shall contain at least twice qualification, detection sets shall include the equivalent of three personnel as many unflawed as flawed grading units e

qualification sets. To qualify new values of essential variables, at least one personnel qualification set is required.

Basis: Clarified the guidance for initial procedure qualifications versus quali ing new values of essential variables.

Page 17 of 21

Request No. 06-GO-601 Table 2 Alternatives to Appendix VIII, Supplement 11 SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR PDI PROGRAM:

FULL STRUCTURAL OVERLAID WROUGHT AUSTENITIC PIPING WELDS The Proposed Alternative to Supplement 11 Requirements (f) Sizing Specimen Alternative: (1) The...least 40% of the flaws shall be open to the inside surface. Sizing sets shall contain a distribution of flaw dimensions to assess (1) The minimum number of flaws shall be ten. At least 30% of the flaws shall sizing capabilities. For initial procedure qualification, sizing sets shall include be overlay fabrication flaws. At least 40% of the flaws shall be cracks open to the equivalent of three personnel qualification sets. To qualify new values of the inside surface.

essential variables, at least one personnel qualification set is required.

Basis: Clarified the guidance for initial procedure qualifications versus qualifying new values of essential variables and is consistent with ld(1) above..

(3) B luAlternative:

(3) Base metal flaws used...circumferentially.

Base metal cracking used for length sizing demonstrations shall be Basis: Clarified wording to. be consistent with Id(1) above.

oriented circumferentially.

(4) Depth sizing specimen sets shall include at least two distinct locations Alternative: (4) Depth sizing specimen sets shall include at least two distinct where cracking in the base metal extends into the overlay material by at least locations where a base metal flaw extends into the overlay material by at least 0.1 inch in the through-wall direction.

0.1 inch in the through-wall direction.

Basis: Clarified wording to be consistent with Id(1) above.

2.0 Conduct of Performance Demonstration The specimen inside surface and identification shall be concealed from the candidate. All examinations shall be completed prior to grading the results and Alternative: The specimen...prohibited:The overlay fabrication flaw test and presenting the results to the candidate. Divulgence of particular specimen the base metal flaw test may be performed separately.

results or candidate viewing of unmasked specimens after the performance Basis: Clarified wording to describe process.

demonstration is prohibited.

2.1 Detection Test.

Flawed and unflawed grading units shall be randomly mixed. Although the boundaries of specific grading units shall not be revealed to the candidate, the Alternative: Flawed...(base metal or overlay fabrication)...each specimen.

candidate shall be made aware of the type or types of grading units (base or Basis: Clarified wording similar to J(e)2 above..

overlay) that are present for each specimen.

2.2 Length Sizing Test (d) For flaws in base grading units, the candidate shall estimate the length of Alternative: (d) For... base metal grading... base metal wall thickness.

that part of the flaw that is in the outer 25% of the base wall thickness.

Basis: Clarified wording/for consistency.

-2.3 Depth Sizing Test.

For the depth sizing test, 80% of the flaws shall be sized at a. specific location Alternative: (a).The depth sizing test may be conducted separately or in on the surface of the specimen identified to the candidate. For the remaining conjunction with the detection test.

flaws, the regions of each specimen containing a flaw to be sized shall be (b) When the depth sizing test is conducted in conjunction with the detection Page 18 of 21

Request No. 06-GO-001 Table 2 Alternatives to Appendix VIII, Supplement 11 SUPPLEMENT 11 - QUALIFICATION REQUIREMENTS FOR PDI PROGRAM:

FULL STRUCTURAL OVERLAID WROUGHT AUSTENITIC PIPORM FL SRRIDG W R H AThe Proposed Alternative to Supplement 11 Requirements PIPING WELDS identified to the candidate. The candidate shall determine the maximum depth test and the detected flaws do not satisfy the requirements of 1. 1(f), additional of the flaw in each region.

specimens shall be provided to the candidate. The regions containing a flaw to be sized shall be identified to the candidate. The candidate shall determine the maximum depth of the flaw in each region.

(c) For a separate depth sizing test, the regions of each specimen containing a flaw to be sized shall be identified to the candidate. The candidate shall determine the maximum depth of the flaw in each region.

Basis: Clarified wording to better describe process.

3.0 ACCEPTANCE CRITERIA 3.1 Detection Acceptance Criteria Alternative: Examination procedures are qualified for detection when:

a. All flaws within the scope of the procedure are detected and the results of the performance demonstration satisfy the acceptance criteria of Table Viii-Examination procedures, equipment, and personnel are S2-1 for false calls.

Examnaton rocdure, euipent andperonnl ae

.b.

At least one successful personnel demonstration has been performed qualified for detection when the results of the performance demonstration satisfy the acceptance criteria of Table VI1-S2-1 for both detection and false meeting the acceptance criteria defined in (c).

calls. The criteria shall be satisfied separately by the demonstration results for

c. Examination equipment and personnel are qualified for detection when the calls.The craigiteriashall ber sa seplayraty bithe dresults of the performance demonstration satisfy the acceptance criteria of Sbase grading units and for overlay grading units.

Table VIII-S2-1 for both detection and false calls.

d. The criteria in (b) and (c) shall be satisfied separately by the demonstration results for base metal grading units and for overlay fabrication grading units.

Basis: Clarified wording to better describe the difference between procedure qualification and equipment and personnel qualifications.

3.2 Sizing Acceptance Criteria (a) The RMS error of the flaw length measurements, as compared to the true Alternative* (a) The...base metal flaws is...position.

flaw lengths, is less than or equal to 0.75 inch. The length of base metal Basis: Clariied wording to be consistent with Jd(J) above.

crtjcldng is measured at the 75% through-base-metal position.

Alternative: This requirement is omitted.

Basis: The requirement for reporting all extensions of cracking into the (b) All extensions of base metal cracking into the overlay material by at least overlay is omitted from the PDI Program because it is redundant to the RMS 0.1 inch are reported as being intrusions into the overlay material, calculations performed in paragraph 3.2(c) and its presence adds confitsion and ambiguity to depth sizing as required by paragraph 3.2(c). This also makes the weld overlay program consistent with the supplement 2 depth sizing criteria Page 19 of 21

Request No. 06-GO-001 Table 3 Modifications to Code Case N-638-1 Code Case N-638-1 Modification/Basis Modification: The maximum area of an individual weld based on the finished surface over theferritic material will not exceed 500 square inches, and the Weld Area depth of the WOL shall not be greater than one-half of the ferritic base metal 1.0(a) The maximum area of an individual weld thickness based on the finished surface shall be 100 sq. inch, Basis: The maximum area of the WOL for the surge line nozzle will be and the depth of the weld shall not begreater than approximately 120 sq-in over the ferritic material. Code Case N-638-3 and one-half of the ferritic base metal thickness.

the associated white paper have been approved by the ASME Code Committees, and provide technical justification for extending the area limitation to 500 sq. inch.

Examination (Referenced below in 4.0(b) para. 1.0(d) Prior to welding the area to be Modification: In lieu of the required ultrasonic examination of 4.0(b) only the welded and a band around the area of at least 11/2 times the component required liquid penetrant examination will be performed. The ultrasonic thickness or 5inch, whichever is less shall be at least 500F.)

examination will be ia rn trmad Ap e

Qs examination will be in accordance with N-504-2 and Appendix Q.

.4.0(b) The final weld surface and a band around the area defined in. para. 1.0 Basis: For the application of the weld overlay repair addressed in this request

(.4.0()

Thale fxaminaweldusing surface and a

ubraroundc mthe s aa efined i

the. appropriate examination methodologies and volumes are provided in Code (d) shall be examined using a surface and ultrasonic methods when the Case N-504-2 and Nonmandatory Appendix Q, Code Case (N-638-1) applies completed weld has been at ambient temperature for at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. The tane f edgwr a ter bead teChie ise eNployed andlis ultr'asonic examination shall be in accordance with Appendix I.3 to any type of welding where a temper bead technique is to be employed and is not specifically written for a weld overlay repair. Code Case N-638-3 has eliminated the requirement to examine a band around the area to be welded, 3 Refer to the 1989 Edition with the 1989 Addenda and later Editionis and and specifies required post weld non-destructive examination of the welded Addenda region only.

Page 20 of 21

Request No. 06-GO-001 Enclosure I Table 3 Modifications to Code Case N-638-1 Code Case N-638-1 I Modification/Basis 4.0(c) requires temperature monitoring by welded thermocouples per IWA-4610(a)

Modification: Preheat and interpass temperatures for the weld overlay will be measured using a contact pyrometer. Interpass temperature will be monitored for the first three layers at each repair location. The interpass temperature measurements will be taken every three to five passes. After the first three layers, interpass temperature measurements will be taken every six to ten passes for the subsequent layers. The heat input from layers beyond the third layer will not have a metallurgical affect on the low alloy steel HAZ.

Basis:. The proposed technique is faster and does not compromise collection of required data, so welded thermocouples are not plannedfor use to monitor interpass temperature during welding. Code Case N-638-3 has clarified this requirement and specifically allows use of pyrometer measurements to determine interpass temperatures. As noted earlier in this document, the NRC has previously approved this type of temperature data.

I N

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